1. Field of the Invention
The invention relates to connectors for use in telecommunications systems and, more especially, to connector sockets (also known as jacks) of the type used for receiving a mating plug that terminates an input cable containing, for example, telephone or computer data lines.
2. Background
One form of connectors that is widely used in the field of telecommunications is the RJ45 type of connectors comprising a modular jack for receiving a compatible modular plug that terminates four twisted wire pairs. These jacks are used both in active telecommunications equipment, for example routers, and passive equipment, for example patch panels. They are designed for making electrical connection with a mating plug.
An RJ45 jack has an array of eight contacts at its front side (called front contacts), conventionally numbered from “1” to “8”, for engaging with respective contacts in the mating plug. As is well-known, front contacts “4” and “5” of the jack are conventionally for connection to a first wire pair on the jack side, contacts “1” and “2” are for connection to a second wire pair, contacts “3” and “6” are for connection to a third wire pair, and contacts “7” and “8” are for connection to a fourth wire pair. In other words, in this type of jack, there is conventionally a region in the array of contacts in which adjacent contacts (i.e. contacts “3” to “6”) belong alternately to different wire pairs while, in the remainder of the array, each pair of adjacent contacts (i.e. contacts “1”, “2”, and “7”, “8”) belongs to one respective wire pair.
It is known that unwanted crosstalk is mainly created by the plug and front contacts of the jack, especially between the inner wire pairs connected to contacts 3 to 6 of the jack. The amount of crosstalk increases with increasing operating frequency and as the number of connectors occupying a particular space is increased. It may even reach a level at which it interferes with, or prevents, the transmission of data.
It has previously been proposed to reduce crosstalk introduced by the mechanical parts of a telecommunications connector by modifying the shape of the front contacts of the jack. This can, however, result in front contacts that have an undesirably complicated shape, or are difficult to assemble and maintain in the required position within the jack, or do not accept and engage consistently with the variety of mating plugs available on the market.
US 2002/0132532 (Henneberger) describes a modular jack of the RJ45 type in which the front contacts have three different geometric configurations, two of the configurations being described as “rearwardly extending” and one of the configurations being described as “forwardly extending”. The described configurations are said to assist in reducing crosstalk between the contacts located at position 3 to 6 of the jack. In other configuration, described in U.S. Pat. No. 6,120,330 (Gwiazdowski), the jack contacts are crossed for the purpose of crosstalk compensation.
It has also been proposed to offer a jack of a telecommunications connector with a printed circuit board (PCB) on which the contacts may be mounted and through which they are connected to the incoming wire pairs, and it has previously been proposed to implement crosstalk compensation on this PCB (see, for example, WO 2005/064755 (Panduit Corp.); US 2008/0090468 (Reeves et al); and U.S. Pat. No. 6,464,541 (Hashim et al)).
It is also known to add at least one other circuit board to the jack which electrical contains compensation components. The above mentioned U.S. Pat. No. 6,464,541 (Hashim et al) discloses a jack with a PCB on which the front contacts are mounted and through which they are connected to the incoming wire pairs and a second PCB comprising contact pads for making electrical contact with free ends of the front contacts. Certain values of capacitance are provided on or within the board between selected pairs of contact pads in order to implement compensation coupling in the connector. The contact pads are connected to the front contacts outside of their signal paths.
US 2009/0305563 (Pepe et al) also disclose a jack comprising more than one PCB within its housing. A first PCB is used for mounting the front contacts and for electrically connecting them to incoming wire pairs. This PCB may comprise electrical compensation components. A second PCB, which may also comprise electrical compensation components, is electrically connected to the front contacts at their free end portion that is outside their signal path. A third PCB, which also comprises electrical compensation components, is electrically connected to the contacts at their intermediate portion that is within their signal path.
In the field of telecommunications jacks there is always the need to further reduce crosstalk, especially in a scenario of constantly increasing band widths. There is further a need of providing jacks that may be produced cost effective. Therefore any simplification in the construction of jacks is desirable as well.